For example, a motion guide apparatus is known which guides the motion of a table of a machine tool. The motion guide apparatus includes a guide rail and a block that is assembled to the guide rail via multiple rolling elements such as balls and rollers in such a manner as to be movable relatively. The table is driven by a drive device such as a ball screw or linear motor. The motion guide apparatus guides the motion of the table. The rolling motion of the rolling elements is used to guide the motion of the table; accordingly, smooth movement of the table can be obtained.
In order to increase rigidity, preload, that is, a load on the rolling elements sandwiched between the guide rail and the block, is applied to the motion guide apparatus. Moreover, a sealing member is mounted on the block. Hence, friction is present in the motion guide apparatus. When the motion guide apparatus is operated under heavy load and/or at high speeds, the motion guide apparatus generates heat due to friction. The heat generation leads to the thermal expansion of the rail and the block to reduce feed accuracy of the table, and results in the thermal expansion of a component to which the rail and the block are attached. The motion guide apparatus needs to be cooled to move the table with high accuracy.
As known motion guide apparatuses, Patent Literature 1 discloses a motion guide apparatus where a coolant groove is formed in a guide rail of the motion guide apparatus, and coolant is supplied into the groove to cool the guide rail. Patent Literature 2 discloses a motion guide apparatus where a coolant passage is formed in a block of the motion guide apparatus, and coolant is supplied into the passage to cool the block.